In earth boring operations, it is very often necessary to establish proper orientation of tooling, packers and the like at the bottom of the hole. In the past, various types of survey instruments have been devised to perform this function. For instance, U.S. Pat. to Boucher No. 2,232,777 discloses the utilization of an optical sensing arrangement in combination with a compass so that when the sensing arrangement is properly aligned with magnetic North on the compass, it will through a rotating prism transmit light to a photocell and, by means of a signal transmitted to the surface, indicate proper alignment with respect to magnetic North. U.S. Pat. to Bergan No. 3,253,341 similarly senses alignment of an instrument in a downhole apparatus by suspension of a compass unit from a cable. A generator and potentiometer are employed such that the repetition rate of the impulses of the generator will control the rotation of the instrument and permit the position of a wiper arm to be varied in response to movement of the compass element with respect to magnetic North. In such devices and others known in the art, operation of the downhole instrument is both controlled and powered from the earth's surface so as to necessitate costly and bulky transmission wires which run for extended distances through the bore and into the bottom of the hole. Moreover, fairly complex and sophisticated sensing circuits have been required in tracking the movement or rotation of the instrument and compass and in establishing proper orientation of tooling or other devices located downhole.